An example of a switching system to which the present invention applies is described in U.S. Pat. No. 5,544,163, Expandable Telecommunications System, the contents of which are hereby incorporated by reference herein. In that system a host computer exercises overall control of the system. Specifically, it exercises control of a plurality of switching nodes that are interconnected by an internodal network For example, it performs call setup and teardown functions by supervising virtual connections among the line interface ports in the switching nodes incorporated in the system. The host also performs various system monitoring functions and it is used in configuring and reconfiguring the system in response to inputs from a system operator. These various functions are described in the above-referenced patent. Communications between the host and the switching nodes are preferably provided by a host network, i.e., a network other than the internodal network which is used in the telecommunications switching function of the switching system.
A single system host was originally contemplated. However, in some environments the host may be overloaded, for example, by a high frequency of call setup and teardown operations and by other functions that may be assigned by the system operator. Moreover various nodes or groups of nodes may be situated in widely separated geographic locations and communications between a single host and all of the switching nodes may be substantially more expensive than distribution of the host functions on a geo-graphic basis. Moreover, the system operator may desire more flexibility in the communication cation of host functions than is available in the prior single-host arrangements.